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How Much Sleep Do You REALLY Need? An Expert Weighs In

As Americans in the 21st century, a good night's sleep (let alone many in a row) can seem as elusive as the Loch Ness Monster—a mere myth. We're glued to our various gadgets and social media accounts, taking work to bed with us, and our personal and professional success seems to get measured against the extent to which we can "do it all" without ever stopping. Meanwhile, we feel the pressure to get the magic eight: those perfect, seemingly unattainable eight hours of sleep we've been told are essential for our health and well-being.

If you worry about achieving the ideal amount of sleep each night, wonder if you really need eight hours or can survive on less, or want to know just how bad it is to chronically under-sleep, you're in luck. We interviewed national sleep expert and behavioural scientist Wendy Troxel, whose research and statements are backed by The National Institutes of Health and a Ph.D. in clinical and health psychology, for the truth about how many hours of sleep you need and much more.

Keep clicking for a major awakening on your sleep habits.

What exactly is sleep and how does the human sleep cycle work? Sleep is a dynamic state consisting of rapid eye movement (REM) sleep and non-REM sleep. REM sleep is where most of our vivid, story-like dreams occur. Non-REM sleep is divided into four stages, with each increasing stage from one to four reflecting a deeper stage of sleep, stage four being the deepest. Stage four is associated with slow-wave brain activity and is thought to be the most restorative stage of sleep. When people fall asleep, most often they progress through the lighter to deeper stages of non-REM sleep, and then transition into REM in cycles spaced approximately 90 minutes apart.

According to a new public health documentary entitled Sleepless in America, a collaboration between National Geographic in conjunction with the National Institutes of Health and The Public Good Projects, which premiered November 30, in addition to crucial brain functions and processes, sleep boosts our immune systems, stabilizes our energy balance by optimising glucose and insulin levels, regulates our appetite and helps control weight gain, and is tied to the overall health of our heart. In addition, it plays a role in stabilizing our mood, as studies have shown that a lack of sleep impacts the hormones related to happiness and depression. In short? It does everything.

In an interview related to the documentary, Matthew Walker, Ph.D., the documentary’s featured expert and director of the Sleep and Neuroimaging Laboratory at the University of California, Berkeley says, “There doesn’t seem to be one major organ within the body, or process within the brain, that isn’t optimally enhanced by sleep, and detrimentally impaired when we don’t get enough.”

The Center for Disease Control and Prevention lists seven to eight as the number of hours of sleep that adults “need” each night, and likely, that’s what you’ve heard your whole life. Where does that number come from? Troxel explains that eight hours is not actually a magic number, but essentially the mathematical average for the range of sleep that most adults report. However, she says, “evidence does support that people who sleep less than six hours per night or those who sleep more than nine hours per night are at increased risk for health consequences as compared to those sleeping seven to eight hours.”

Though there are definitely individual differences in the need for sleep, Troxel confirms that for most adults seven to eight per night is considered optimal for health and functioning. “People who sleep less than six hours a night are at increased risk for a host of adverse mental and physical health problems, including obesity, heart disease, diabetes, and even mortality.”

According to “Sleep Disorders and Sleep Deprivation,” a compendium of sleep research studies published by The Institute of Medicine and referenced in the documentary, studies have shown that when subjects in their 20s got less than six hours of sleep each night, they were 7.5 times more likely to have a higher body mass index than people who got the recommended seven to eight hours, even when family history, exercise, and other factors were considered. It is thought that inadequate sleep lowers levels of leptin, a hormone that controls appetite, and increases levels of ghrelin, which cues hunger.

Additional studies have shown links between adults consistently getting six or less hours of sleep a night and increased likelihood of developing diabetes, compromised immune system, high blood pressure, and stroke.

If all of that isn’t enough to scare you into sleeping eight hours a night, we don’t know what is!

At this point, you might be feeling defensive about your unique ability to function highly and perform optimally on less than the rest of us. But hold that thought: Troxel tells us that studies show that very few people are naturally “short sleepers,” however, we tend to convince ourselves that we can function just fine with less than the optimal amount of sleep. “Studies also show that the effects of sleep deprivation (even just sleeping a few hours less than the optimal eight) have a cumulative effect on our ability to think and our behaviour. Moreover, we are really terrible judges of our own sleep-related impairment, so you might think you are functioning just fine on three or four hours of sleep, but objective measures would likely tell you a different story,” she says.

We wanted to know if it’s ever possible to make up for those nights when we fall short—way short—of sleeping the recommended amount. Troxel told us that while our bodies can recover some amount of sleep debt over time, one night of good sleep is not enough to “pay back” chronic debt.

We also wanted to know how the age-old question of quality versus quantity applies to sleep. If you only sleep five hours, but it’s really good, deep sleep (or at least feels that way), is that better than sleeping eight but tossing and turning? “Both quality and quantity are important,” says Troxel. “Someone who says they sleep nine hours per night, but are up half the time or are tossing and turning, is not getting good quality sleep. Ways to improve sleep quality include setting a consistent bedtime and most importantly, a consistent wake time, removing distractions from the bedroom (i.e. any electronic device), keeping the room cool, minimising light and noise, and keeping the bed for sleep and sex only.”

If you are having a bad night of sleep and can’t fall or can’t stay asleep, Troxel says the best solution is to get out of bed, do something relatively boring but distracting (i.e. reading), and then return to bed when feeling sleepy again.

If you get a bad night of sleep, Troxel says it’s best to stay active during the day after and avoid focusing on sleep loss as the sole cause for “all that ails you.” “Even though getting an optimal amount of sleep is recommended, we all have bad nights once in a while,” she says. “However, if you put too much pressure and focus on your need for sleep then you might end up feeling anxious and worried about getting enough sleep, which unfortunately will perpetuate a cycle of poor sleep,” she says.

Naps are helpful for some people the day after a bad night of sleep, provided that they are short power naps, which means 30 minutes or less, and that they happen earlier rather than later in the day—before 2:00 p.m. “Any later in the day, and napping can interfere with nighttime sleep by taking away some of the homeostatic drive for sleep which builds throughout the day. Long naps can leave one feeling groggy and disoriented, as one is more likely to drift into deeper stages of sleep,” she explains.

With everything we now know about the importance of getting the recommended seven to eight hours of sleep each night—and the effects of not doing so—we had to ask Troxel one simple thing: her number-one sleep tip. “Maintain a consistent wake-up time,” she told us. Yes, that means even on the weekends.

Though we don’t often prioritise it as such, sleep is a fundamental building block of overall health. The studied risks of sleeping six or less hours of sleep a night are downright frightening, and underscore the critical importance of sleep. As one researcher recently put it, “sleep is not a luxury to occasionally get in sufficient amounts,” it’s as important as diet and exercise for living a healthy, illness-free life—not to mention one where you’re in a good mood and not at risk of a wider waistline.

That said, it’s also important, as Troxel noted, to not get obsessed as that only leads to pressure and anxiety that in turn undermines the very thing you’re after: a sound night of sleep. Do your best to prioritise getting enough sleep each night, the same way you prioritise your workouts, and take the steps you need to take in terms of streamlining your bedroom routine and staying productive during the day so that you’re not up in the wee hours of the night.

We don’t know about you, but Troxel’s tips, and the new documentary, Sleepless in America, have us completely motivated us to make sleep a top priority in our life. We’ll be waking up at 7 a.m. this weekend (part of maintaining that consistent wakeup time). How about you?